Engineering epitaxial interfaces for topological insulator – superconductor hybrid devices with Al electrodes
Creators
-
Jalil, Abdur Rehman1, 2
*
- Schmitt, Tobias W.1, 2
-
Rüßmann, Philipp3, 4
*
- Wei, Xian-Kui5
- Frohn, Benedikt1, 2
- Schleenvoigt, Michael1, 2
- Wittl, Wilhelm1
- Hou, Xiao2, 6
- Schmidt, Anne1, 2
- Underwood, Kaycee1
- Bihlmayer, Gustav3
- Luysberg, Martina5
- Mayer, Joachim5, 6
- Blügel, Stefan3
- Grützmacher, Detlev3, 2
- Schüffelgen, Peter1, 2
- 1. Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- 2. JARA-FIT (Fundamentals of Future Information Technology), Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
- 3. Peter Grünberg Institute (PGI-1), Forschungszentrum Jülich, 52425 Jülich, Germany
- 4. Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany
- 5. Ernst Ruska-Centre (ER-C) for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- 6. Central Facility for Electron Microscopy (GFE), RWTH Aachen University, 52074 Aachen, Germany
* Contact person
Description
Proximity-induced superconductivity in hybrid devices of topological insulators and superconductors offers a promising platform for the pursuit of elusive topological superconductivity and its anticipated applications, such as fault-tolerant quantum computing. To study and harness such hybrid devices, a key challenge is the realization of highly functional material interfaces with a suitable superconductor featuring 2e-periodic parity-conserving transport to ensure a superconducting hard-gap free of unpaired electrons, which is important for Majorana physics. A superconductor well-known for this characteristic is Al, however, its direct integration into devices based on tetradymite topological insulators has so far been found to yield non-transparent interfaces. By focusing on Bi₂Te₃-Al heterostructures, this study identifies detrimental interdiffusion processes at the interface through atomically resolved structural and chemical analysis, and showcase their mitigation by leveraging different interlayers – namely Nb, Ti, Pd, and Pt – between Bi₂Te₃ and Al. Through structural transformation of the interlayer materials (X) into their respective tellurides (XTe₂) atomically-sharp epitaxial interfaces are engineered and further characterized in low-temperature transport experiments on Al-X-Bi₂Te₃-X-Al Josephson junctions and in complementary density functional theory calculations. By demonstrating functional interfaces between Bi₂Te₃ and Al, this work provides key insights and paves the way for the next generation of sophisticated topological devices.
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References
Preprint (Preprint where the data is discussed) A. R. Jalil, T. W. Schmitt, P. Rüßmann, X.-K. Wei, B. Frohn, M. Schleenvoigt, W. Wittl, X. Hou, A. Schmidt, K. Underwood, G. Bihlmayer, M. Luysberg, J. Mayer, S. Blügel, D. Grützmacher, P. Schüffelgen, under review (2024)
Software (Source code for the AiiDA-KKR plugin) P. Rüßmann, F. Bertoldo, J. Bröder, J. Wasmer, R. Mozumder, J. Chico, and S. Blügel, Zenodo (2021), doi: 10.5281/zenodo.3628251
Journal reference (AiiDA-KKR method paper) P. Rüßmann, F. Bertoldo, and S. Blügel, The AiiDA-KKR plugin and its application to high-throughput impurity embedding into a topological insulator. npj Comput Mater 7, 13 (2021), doi: 10.1038/s41524-020-00482-5
Software (Source code of the JuKKR code) The JuKKR developers, JuDFTteam/JuKKR: v3.6 (v3.6), Zenodo. (2022), doi: 10.5281/zenodo.7284739
Journal reference (Kohn-Sham Bogoliubov-de Gennes method paper for JuKKR) P. Rüßmann and S. Blügel, Phys. Rev. B 105, 125143 (2022), doi: 10.1103/PhysRevB.105.125143
Software (Source code of the FLEUR code) D. Wortmann et al., FLEUR, Zenodo (2024), doi: 10.5281/zenodo.7576163